合成,表征和光学特性单分散性合性氧化化物
Yanhou Geng1, Anita Trajkovska, Dimitris Katsis
1Department of Chemical Engineering, Center for Optoelectronics and Imaging, University of Rochester, 240 East River Road, Rochester, New York 14623-1212, USA.
Journal of the American Chemical Society
|July 11, 2002
概括
研究人员合成了奇拉性奥利戈烯,发现链条长度决定了固体形态. 较长的寡合体表现出胆固醇等态性,导致玻璃膜中增强的循环极化光和循环二极化.
科学领域:
- 有机化学 有机化学
- 材料科学 材料科学 材料科学
- 聚合物科学 聚合物科学
背景情况:
- 状有机分子对于先进的光学和电子应用至关重要.
- 控制寡合体的固态形态是调整其性质的关键.
- 奥利戈烯为开发新的功能性材料提供了一个多功能平台.
研究的目的:
- 为了合成和表征一系列单分散的性氧化.
- 研究链条长度对固体形态和光学特性的影响.
- 探索有序状结构的形成及其对循环极化光辐射的影响.
主要方法:
- 合成具有不同链条长度的单分散性性化氧化.
- 使用NMR,GPC和DSC等技术进行表征.
- 使用X射线衍射和光学显微镜分析固体形态.
- 测量循环二极化 (CD) 和循环极化光 (CPL).
- 分子动力学模拟以了解结构-属性关系.
主要成果:
- 从二次体到四次体的奥利戈烯是无形的.
- 五合体到六合体体表现出不同稳定性的胆固醇等态.
- 纯净的片显示出明显的CD和高效的CPL,表明了性组合.
- 经过热处理后,一种经过修饰的非聚合物形成了一个单域玻璃状胆固醇膜.
- 胆固醇膜表现出CD和CPL手性逆转的数量增加.
结论:
- 链条的长度是确定奇拉性氧化的固态形态的一个关键因素.
- 在较长的寡合体中,胆固醇中型形成使得增强的奇拉光学特性成为可能.
- 热处理可以诱导有序的,单主体的玻璃状胆固醇膜,具有独特的光学反应.
- 分子动力学模拟为观察到的奇拉光学现象的分子起源提供了洞察力.
相关概念视频
02:54Classification of Elements and Compounds
Pure substances consist of only one type of matter. A pure substance can be an element or a compound. An element consists of only one type of atom, while a compound consists of two or more types of atoms held together by a chemical bond. Elements are classified as atomic or molecular based on the nature of their basic units.
Compounds are pure substances composed of two or more elements in fixed, definite proportions. Compounds are classified as ionic or molecular (covalent) based on the bonds...
Compounds are pure substances composed of two or more elements in fixed, definite proportions. Compounds are classified as ionic or molecular (covalent) based on the bonds...
02:17Synthesis and Decomposition Reactions
Synthesis and decomposition are two types of redox reactions. Synthesis means to make something, whereas decomposition means to break something. The reactions are accompanied by chemical and energy changes.
02:46Covalent Bonding and Lewis Structures
Compared to ionic bonds, which results from the transfer of electrons between metallic and nonmetallic atoms, covalent bonds result from the mutual attraction of atoms for a “shared” pair of electrons.
02:58Properties of Transition Metals
Transition metals are defined as those elements that have partially filled d orbitals. As shown in Figure 1, the d-block elements in groups 3–12 are transition elements. The f-block elements, also called inner transition metals (the lanthanides and actinides), also meet this criterion because the d orbital is partially occupied before the f orbitals.
01:23Properties of Organometallic Compounds
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
01:08Covalent Bonds
Overview
When two atoms share electrons to complete their valence shells, they create a covalent bond. An atom's electronegativity—the force with which shared electrons are pulled towards an atom—determines how the electrons are shared. Molecules formed with covalent bonds can be either polar or nonpolar. Atoms with similar electronegativities form nonpolar covalent bonds; the electrons are shared equally. Atoms with different electronegativities share electrons unequally, creating polar bonds.
When two atoms share electrons to complete their valence shells, they create a covalent bond. An atom's electronegativity—the force with which shared electrons are pulled towards an atom—determines how the electrons are shared. Molecules formed with covalent bonds can be either polar or nonpolar. Atoms with similar electronegativities form nonpolar covalent bonds; the electrons are shared equally. Atoms with different electronegativities share electrons unequally, creating polar bonds.